Twin cylinder motorcycle engine

Abstract

A rocker box, pushrod assembly, oil delivery system, tappets and tappet guides are provided for an engine, particularly a shovelhead motorcycle engine. The rocker box includes a separable upper portion and lower portion with a seal for sealing the upper portion and lower portion when coupled together. The pushrod assembly includes an adjusting unit that collapses into a pushrod shaft. The oil delivery system includes an oil passageway(s) in a rocker shaft of a rocker arm assembly, and at least one of an oil passageway(s) in a rocker box and an oil passageway(s) in a pushrod assembly.

Description

BACKGROUND OF THE INVENTION [0001] This application is a divisional of application Ser. No. 10 / 845,126 filed May 14, 2004, the entire disclosure of which is incorporated by reference herein.FIELD OF THE INVENTION [0002] The present invention relates generally to rocker boxes, pushrods, tappets, tappet guides, and oil delivery systems for combustion engines, and more particularly to such devices as applied to twin cylinder motorcycle engines. DESCRIPTION OF THE RELATED ART [0003] Conventional rocker boxes typically involve a cast structure with parts (e.g., rocker arms, pushrods, etc.) extending into and / or mounted within the cast structure. Due, in part, to the integral nature of cast rocker boxes, installing, removing, and adjusting the parts extending into and / or mounted within the cast rocker box is difficult. As such, in many instances the entire cylinder head and rocker box must be removed from the motorcycle in order to access the parts positioned therein. Even after removal o...

AI Technical Summary

Benefits of technology

The separable rocker box design facilitates easier maintenance and aesthetic finishing, reduces complexity and size, and ensures consistent clearances and oil delivery efficiency, while the collapsible pushrod assemblies simplify installation and removal without requiring cylinder head removal.

Problems solved by technology

Due, in part, to the integral nature of cast rocker boxes, installing, removing, and adjusting the parts extending into and / or mounted within the cast rocker box is difficult.

Even after removal of the cylinder head and rocker box, the movable parts extending into and / or mounted within the cast rocker box are still difficult to access.

Additionally, the cast structure of conventional shovelhead rocker boxes tends to have a rough outer surface, which is difficult to finish into a smooth, more aesthetically pleasing surface.

Further, this surface is particularly difficult to polish and / or chrome plate due to inconsistencies and defects inherent in parts produced by known casting processes.

As such, it is difficult to manufacture a rocker box with an aesthetically pleasing outer surface.

This rocker support increases the part count and complexity of the rocker box assembly, and reduces the structural rigidity with which the rocker arms are supported.

Further, the added space for supporting the breather apparatus needlessly increases the size of the device in motorcycle engines which do not require a breather apparatus at all.

Not all motorcycle engines, however, are configured to provide oiling via the pushrods.

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